Buy.com has this 2-pack insulated beverage "thermos" for just $6.99 with free shipping. While not huge at just 0.5L each, it's enough for strong coffee or tea. Also, it's "thermos," and not the actual Thermos brand. However, at just $3.50 a pop, it's a nice deal.
500ML STAINLESS STEEL THERMOS-TYPE 2-PACK SALE